Abstract: Using Biome-BGC model can simulate vegetation productivity through the coupling of water and CO₂ exchange processes between vegetation，soil and atmosphere, but the soil water balance module is not perfect enough, leading to a large deviation between simulated and observed values under condition of a long time no precipitation. Aiming at this problem, this paper improved and adjusted the equation of stomatal conductance stressed by soil water, the calculation formula of evapotranspiration, and the process of soil water loss in Biome-BGC model. Using this improved model, the evapotranspiration and vegetation productivity in Harvard Forest area were simulated, and compared with field observations. The accuracy of simulated results by the improved model enhanced obviously, with the evapotranspiration R² between simulated and observed values increased from 0.483 to 0.617, NEE R² increased from 0.658 to 0.813, root mean square error (RMSE) of annual evapotranspiration decreased averagely by 48.7%, and annual sum squared error (ASSE) of NEE decreased averagely by 39.8%, which suggested that the simulated results by using the improved model were more close to the observed results.

Key words: East China Sea, Mesocosm, Interspecific competition